The Redmi 3S series is deservedly considered one of the most reliable devices in the budget segment, but even they eventually need to replace the battery. The lithium polymer battery tends to degrade after hundreds of charge cycles, which leads to rapid discharge or spontaneous shutdown of the gadget. Unlike models with a fixed case, the replacement procedure is relatively simple here, but requires accuracy and understanding of the smartphone device.
Before starting the dismantling, you need to prepare the workplace and the necessary tools. Lack of dust and static electricity are key factors in success, as getting rubbish under the screen or on the board can put the device out of order. You will need a thin plastic blade, a set of screwdrivers (usually cross PH00 or PH000) and, preferably, a sucker for a careful lifting of the cover.
It is important to understand that the Xiaomi Redmi 3S has a unified body similar to the 3X and Prime models, but the location of the plumes may differ.Safety is a top priority, so before starting work, be sure to turn off the phone and make sure that the battery charge does not exceed 25% to minimize the risks of accidental short circuit contacts.
Tools and workplace preparation
Quality preparation is half the success of repair work, the organization of space allows you not to lose small screws and damage fragile components, it is recommended to use a magnetic mat or ordinary white paper, which is clearly visible all the details, the light should be bright and directed to clearly distinguish the places of attachments.
To disassemble the Redmi 3S, you'll need a minimal toolkit, which can be found in any electronics repair kit. The main tool will be a mediator or plastic card, which is convenient to snap latches without scratching plastic. Metal tools are best avoided, as they can damage internal cables.
Don't forget to skim your hands or wear antistatic gloves. Fat marks on the internal components can lead to oxidation of contacts over time. Also, there should be a screw folding container at hand, preferably with separation by disassembly stages.
- 🔧 A set of precision screwdrivers (cross and flat)
- 📱 Plastic suction cup or smartphone opener
- 💳 Plastic card or mediator for slashing the body
- 🧤 Antistatic gloves and tweezers with dielectric tips
If you don't have a professional set, you can do with a minimal set, but the quality of the tools directly affects the result. Dumb screwdrivers can rip off the screw hats, which will turn a simple repair into a difficult problem with drilling the fasteners.
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Use a magnetic mat or a sheet of paper with markup to spread the screws in order of their extraction – this will help not to confuse anything during assembly.
Rear cover removal process
Removing the back is the first and most important step, because this is where plastic latches are most often broken. The design of the Xiaomi Redmi 3S case involves two screws hidden under decorative plugs or located at the bottom, and a series of clips around the perimeter.
Carefully insert the plastic blade into the junction between the frame and the lid at the bottom corner. The motion should be sliding, not stabbing, so as not to damage the side face. Walk the tool around the perimeter, gradually snapping the locks. You will hear a characteristic click when the latch is released.
⚠️ Warning: Don't try to open the lid with force. Plastic on older devices becomes brittle, and excessive force will lead to cracks on the ends of the case.
Once all the latches on the sides and bottom are free, you can lift the lid. There's often an extra lock at the top of the camera. You can move slowly to control the force. If the lid doesn't lend itself, make sure there's a screw that you might have missed.
Disconnection of plumes and protection of the board
When you take the lid off, you see the inside of the smartphone, and the battery takes up most of the space, but it's covered by a metal shield covering the motherboard, and it's mounted with multiple screws of different sizes, so it's important to remember where they are.
Unscrew all the screws that hold the metal shield. 10-12 Short screws should not be screwed into long holes, as this can damage the circuit board or break the insulation. Use a magnifier for a better view.
When the protection is removed, you'll see connectors connecting the battery, the screen and the button plumes to the main board. The first thing you need to do is turn off the battery connector. Use a plastic blade or nail to do this, gently lifting the connector up. Don't pull the wires!
- 🔌 Turn off the main battery plume first
- 📸 Carefully remove the main camera plume connector
- 🔊 Disconnect the plume of the lower board (dynamics and microphone)
- 🖥️ Carefully turn off the display plume (if you need a full disassembly)
Once all the plumes are turned off, the metal plate can be removed completely, the motherboard and battery mounts are now open, and visually inspect the board for swollen capacitors or corrosion marks that may have been caused by the old battery.
☑️ Check before removing the battery
Removing the old battery
In the Redmi 3S, the battery is attached to the body with double-sided tape. The glue dries over time, but often holds the battery tight enough. The mechanical force here needs to be applied wisely so as not to damage the battery itself, which can be dangerous.
On the bottom of the battery there is usually a special tongue.-pull If you have a tab that you can pull on, if you have it, you can pull it carefully, and you can try to lift the battery, and if you don't have a tongue or it's gone, you'll have to use a plastic card, put it between the battery and the case, and you'll have to do the sawing movements.
⚠️ Note: It is strictly forbidden to use metal objects (knives, screwdrivers) to smack the battery.
If the battery is very tight, you can warm up the back of the body with a hair dryer a little bit, and the temperature should not exceed 60-70 degrees Celsius, so as not to melt the plastic parts, the warm air will soften the adhesive base, and it will be easier to remove the element.
After you remove the old battery, compare it to the new one. The battery model should match (usually BM32 or similar) and pay attention to the location of the contacts and the thickness of the cell so that it fits freely into the housing.
What to do if the battery is blown?
Installation of a new power supply
Before installing a new battery, you need to prepare a seat, and the residue of the old glue must be carefully removed so that the new battery lays flat and tight. Use isopropyl alcohol or a special solvent for the adhesive, but make sure that the liquid does not get into the contacts.
A new battery is often already covered with adhesive layer, covered with a protective film. If there is no adhesive, use a special double-sided electronics tape (e.g. 3M). Apply two strips around the edges, avoiding the center where the battery controls (BMS board) are located.
Carefully insert the battery into the niche, matching the contacts with the connector on the board. Don't insert the connector before the click immediately - first make sure that the battery is flat. Then gently press the connector until the characteristic click. Connection quality control is critical for stable phone operation.
| Parameter | Old battery | New battery | Norma. |
|---|---|---|---|
| Capacity | ~2500 mAh | 4100 mAh | 4000-4100 mAh |
| Tension. | 3.85V | 3.85V | 3.8V - 3.85V |
| Thickness | Bloated. | Standard. | Free of deformities |
| Weight. | Easy to normal. | Standard. | ~80-90 grams |
Once installed, check if the battery is interfering with the installation of the protective metal plate. If everything falls into place without gaps, you can proceed to the final assembly. Make sure that the protective film from the contacts of the new battery is removed before connecting.
Device assembly and initial start
You do the reverse assembly. You put a metal plate in there and you twist all the screws. The twisting order is not as important as the uniformity of the force, but you'd better start with the central screws and move to the edges, and that's going to make sure the board is tight.
Connect all the plumes you've previously disabled. Make sure each connector is locked and locked. Pay special attention to the display plume and touchscreen, as their poor contact can lead to a broken screen or "dead zones."
Close the case by snapping all the clips around the perimeter. Press the edges of the case until you hear the uniform clicks. Then screw the two external screws at the bottom of the device. The final test is best done before the external screws are fully twisted, in case you have to redo something.
⚠️ Warning: Do not turn on your phone if you smell burning or see sparkling in the contact area.
Turn on your smartphone with the power button. If the device is booted, check the charge level and sensor performance. It is recommended to immediately put the phone on charge, as new batteries often come with minimal charge for storage.
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Proper calibration of the new battery: after installation, fully discharge the phone before turning off, then charge to 100% when off, and only then turn on.